box for fosgate 12 subs

I built a box for 2 fosgate 12" subs exactly to the specs that was in the manual that came with them. They are the Power series subs, and I built them with 1 cubic foot per sub. I have built several boxes before, with no problem. These sound like they don't have enough airspace. The person that I built it for is using an older model Zeus 600 watt amp. He had it pushing 2 15" MTX subs before, so I know it is not the amp. I built that box too. He took it to a stereo shop, and they said it looks like it is the right size, but that they always build their boxes bigger than the recommended size for all subs. Any ideas on what is wrong? They are in a sealed box. Thanks, Lewis'85 Toy

Is there air escaping from it somehow? Any pictures?

try polyfil

Did you take into account the volume displacement of the subwoofers themselves? When dealing in small boxes this is an even more critical factor. Do you have another larger box that you can try one of them in to test the theory that the box is too small?

Thanks for the advice. Yes I accounted for the displacement of the subs. And the box is sealed real tight. I am going to build a larger box and see if it helps. I have never ran into this problem before, but I will try a bigger box and see what happens. Thanks, Lewis'85 Toy

Weird, I've never had a problem with my 12" Fosgate woofer and its in a .8-.9cuft box. Its loud as u know what with 400 watts run'n to it. What series sub is it? Mine is an older Punch HE (RFP3812) and its working fine with a smaller box. I've also played Z's and HE2's in smaller boxes w/o problems so I'm kinda baffled that a little under the specs with the air space would cause distortion."Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

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I'd also say try polyfill, it will actually affect the sound waves inside the box and sound like it has more airspace.  I used to have a pair of the older RF XLC's and boy they require way too much air space!  The box I had to build was the size of a coffin in my trunk, I wish I would have known about fiberglass 3 years ago...Im a fiberglass whore!!

1 ft3?? thats maybe ok for a 10 sealed(rest assured i know what they say!!!) i am willing to bet i get as much,only lower bass, from an 8" ported in 1ft3, just as a rule:(as with anything,there are a FEW exeptions,i try to make sure they are limitations!) 8"- 1 ft3 10" - 2 ft3 12" -3.5 ft3 15" - 6 ft3 (min) this is more for ported,but at least 1/2 the volume for sealed(w/polyfill) i just try not to waste(a little extream,but i try to get the most out of what i sell/build) my time,or my customer's money on bigger woofers,when i can get MORE out of a smaller woofer done right.. personnally i am more impressed with an 8" that sounds like a 12",then a 15" that sounds like a 10".. try an aperiodic,it will ;at least; give you lower bass,and still handle power.. now to stir things up.. I am absolutely correct on this one,do ALOT of research b4 you say what you are going to say.. which box has more pressure to handle? a ported or sealed? ported of course.. the reason is the same reason that a woofer handles more power in a PROPERLY constructed ported box..by at least 50%,sometimes more;depending.. this is because of the control a port exerts on the woofer.. keeping it from over exerting when driven hard,yes air can get in and out, but we arent dealing with just air like what a vacuum cleaner puts in/out,we are dealing with waves,the port doesnt let out air when it isnt supposed to! ,the same air it let more of into it on the last excursion that didnt need the control..is the same air that causes the pressure to be greater when it should be.. oh well,thats probably beyond boxes 101,but keep it in mind! something to talk about.. be careful about port calculators, make sure you are dealing with calculations for a lined box! unless you have no parallel sides!(HA,you have any idea how much a truly non parallel box should cost?!?!) 'Stereo' Mike

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